As a lens that magnifies an image of a sample serving as an observation object, a solid immersion lens (SIL: Solid Immersion Lens) is known. A solid immersion lens has a predetermined shape such as a hemispherical shape or a hyperhemispherical shape called a Weierstrass sphere, that is a microlens of approximately 1 mm to 5 mm in size. Then, provided that the solid immersion lens is installed so as to be put in close contact with the surface of a sample, its numerical aperture (NA) and magnification are both increased, which enables an observation of the sample with high spatial resolution.
As a solid immersion lens holder that holds such a solid immersion lens, for example, solid immersion lens holders disclosed in Patent Documents 1 to 3 are known. The solid immersion lens holder disclosed in Patent Document 1 is configured to support a solid immersion lens in the gravity direction in a state in which the bottom surface of the solid immersion lens protrudes downward through an opening. Further, in Patent Document 2, there is disclosed the holder having a lens holding portion that holds a solid immersion lens which is not fixed to be in a free state. Further, in Patent Document 3, there is disclosed the configuration in which a solid immersion lens holder is disposed in front of an objective lens.